The defiberizing drum as currently known and long used is generally implemented in the form of a cylinder of several meters in length and a diameter of approximately two meters. The cylinder casing is formed of two portions, the first being non-perforated and the second perforated. The cylinder is normally mounted for use in a slightly inclined position or orientation so that the outer end of the first, imperforate portion is disposed higher than the outer end of the second, perforated portion. The cylinder interior, as circumferentially bounded by the casing, is further divided into two portions by a partition wall which separates the non-perforated portion from the perforated portion of the casing. An opening--which may, in accordance with the cylinder type and producer, by either symmetric or asymmetric, and round or of some other shape--is defined in the partition wall and enables fluid and particulate communication between the two portions of the cylinder. The outer end of the first or relatively raised portion of the cylinder is provided with means for feeding waste paper to that relatively lower portion of the cylinder bounded by the non-perforated portion of the casing. This first portion of the casing is, moreover, usually provided with one or a plurality of axial ribs, the purpose of which is to raise or lift upwards, as the cylinder is operatively rotated, the waste paper fed to the cylinder and to then permit it to descend or fall downwards once again; the waste paper, by virtue of this repetitive and frequent movement, defiberizes thereby gradually forming a relatively homogeneous fiber suspension with water which is also supplied to the cylinder. As the pulp flows toward the partition wall separating the two longitudinally-defined portions of the cylinder, this mixture homogenizes whereby it may be transferred through the partition wall opening into the perforated portion of the cylinder in which the suspension fraction, which is sufficiently defiberized, passes through the casing perforations and flows outwardly from the second portion of the cylinder for further treatment of the accept. The undefiberized fraction, or that fraction otherwise including particles that are larger than the perforation openings, is on the other hand discharged from the distal end of the relatively lower, cylinder second portion for reject treatment.
When treating most impurities the defiberizing drum operates in the above-described manner; experience has, however, demonstrated that if the waste paper or like material being treated contains thread-like impurities such as wire, wire rope or the like, such impurities are not transferred through the opening in the partition wall of the drum to the perforated portion of the drum from which they can then pass to mix with the reject. Instead, they accumulate in the non-perforated portion of the drum, initially forming a spherical accumulation that gradually increases in size into a cigar-like ball or mass that extends the full length of the drum. The presence of this kind of ball or mass weakens the operation of the drum, reduces its effective capacity and easily breaks or damages the inner ribs of the cylinder, thus requiring considerable reparation costs and causing extended periods of lost use of the defiberizing drum assembly. Moreover, the discharge or removal of a large wire ball from the drum is both difficult and tedious.